FILE - In this Thursday, Feb. 4, 2016, file photo, a medical researcher uses a monitor that shows the results of blood tests for various diseases, including Zika, at the Gorgas Memorial laboratory in Panama City. The U.S. Food and Drug Administration said Wednesday, March 30, 2016, they are granti

The Associated Press

FILE - In this Thursday, Feb. 4, 2016, file photo, a medical researcher uses a monitor that shows the results of blood tests for various diseases, including Zika, at the Gorgas Memorial laboratory in Panama City. The U.S. Food and Drug Administration said Wednesday, March 30, 2016, they are granting use of an experimental blood test to screen blood for Zika virus, an emergency step that will help protect local blood supplies from the mosquito-borne virus. (AP Photo/Arnulfo Franco, File)

FILE - In this Thursday, Feb. 4, 2016, file photo, a medical researcher uses a monitor that shows the results of blood tests for various diseases, including Zika, at the Gorgas Memorial laboratory in Panama City. The U.S. Food and Drug Administration said Wednesday, March 30, 2016, they are granting use of an experimental blood test to screen blood for Zika virus, an emergency step that will help protect local blood supplies from the mosquito-borne virus. (AP Photo/Arnulfo Franco, File) (The Associated Press)

FILE - In this Thursday, Feb. 4, 2016, file photo, a medical researcher uses a monitor that shows the results of blood tests for various diseases, including Zika, at the Gorgas Memorial laboratory in Panama City. The U.S. Food and Drug Administration said Wednesday, March 30, 2016, they are granting use of an experimental blood test to screen blood for Zika virus, an emergency step that will help protect local blood supplies from the mosquito-borne virus. (AP Photo/Arnulfo Franco, File)